Interpretive Summary: Microorganisms and higher plants have evolved together as distinct systems in which each organism benefits the other. These associations are referred to as mutualisms. The microorganism lives within the plant and are referred to as an endosymbiont or endophyte. The presence of endophytic microbes impacts the ecology of host plants, often increasing fitness traits, and may also affect animal and humans if infected plants are consumed due to toxins produced by the fungus. There is great potential to utilize symbiotic associations such as in the production of crops with minimal use of water, fertilizers, and pesticides. Recent interest has focused on endophytic microbes for their pharmaceutical potentials such as the anticancer drug taxol. This book represents the compilations of writings that deal with the morphology, physiology, ecology, genetic, molecular biology, and evolution of endophytic microbes. The book is the result of the Second International Symbiosis Society Meeting in Woods Hole, MA, where an international group of scientists met to discuss the agricultural importance of this group of organisms. One RRC scientist in collaboration with James White, Rutgers University, who served as Co-Chairs of the Woods Woods Hole Symposium, are editors for the collective writing of over 30 30 leading international authorities for the book Microbial Endophytes. The book consists of 488 text pages, an index, and over 1700 references and will serve as an abundant resource for mycologists, plant physiologists, botanists, evolutionary biologists, ecologists, toxicologists, agronomists, and agricultural engineers.